Equipressure vapor generator and method of operating same



April 3, E951 E. MERCIER EQUIPREssURE VAPOR GENERATOR ANO METHOD OF OPERATING SAME 4 Sheets-Sheet l Filed July 9, 1949 u fm? MMP/Emme pril 3, 1951 E. MERCIER 2,54735 EQUIPRESSUEE VAPOR GENERATOR AND METHOD OF OPERATING SAME Filed July 9. 1949 4 Sheets-Sheet 2 fgg'x/l 79 l I l. `l i l l I N V EN T 01. frm/5f Meiner @CM/M7 47m/WE Y April 3, i951 E. MERCIER 2,547,135

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' Y EQUIPREssURE vAPoR GENERATOR AND METHOD oF OPERATING SAME Filed July 9, 1949 4 Sheets-Sheet 4 t JNVENTOR.

f I Kiwi/s en/W I H 60 BY A 3 l l A 70 5 67\62 Q 6 Patented Apr. 3, 1951 EQUIPRESSURE VAPOR GENERATOR AND METHOD OF OPERATING SAME Ernest Mercier, Paris, France, assigner, by mesne assignments, to Moore, Inc., Atlanta, Ga., a corporation of Georgia Application JulyS, 1949, Serial No. 103,893 In France September 15, 1942 This invention relates to the generation' of vapor from a liquid by heat developed in the combustion of fuel. The invention more especially relates to the generation of a vapor at an elevated pressure for the development of power therefrom concomitantly with the production oi combustion gases at an elevated pressure for developmentfof power from these gases. The invention in a particular feature thereof relates to the control of the generation of the vapor and of the production of the combustion gases to secure operation at pressures of the vapor and of the gases which are in a predetermined relation.

It has been proposed heretofore to generate steam at pressures of 80 to 100 atmospheres absolute, but in generating steam at such pressures all of the steam and water confining parts of the boiler of necessity have been of heavy construction to withstand the internal pressure. This is true not only when the boiler is red under low pressure combustion conditions, but also when high pressure combustion of the order taught 'in the prior art is mentioned. .In operating under ow pressure combustion conditions, the pressure in the combustion chamber is ordinarily kept at about atmospheric pressure orv only slightly above atmospheric pressure, i. e., in the range of 1/2 inch of water pressure up to to 12 inches of water pressure. chambers such pressures slightly above the atmospheric pressure have been utilized to prevent or minimize the leakage of air into the combustion chamber ordinarily constructed of refractory material so as to control and improve the eiioiency of combustion or to provide the pressure for producing rapid flow of the gas over the usually extensive heating surface and through tortuous gas passages.

In conventional combustion' 17 Claims. (Cl. 122-333) 1n order to operate under higher pressure com- I bustion conditions it is necessary te employ a pressure confining casing within which the steam generating elements may be disposed in heatreceiving relation to the combustion gases formed therein. It has been proposed to discharge the combustion'gases produced in such a vapor gen- ,erating system to a gas turbine or other gas 'utilizing prime mover. To avoid the use of thick wall casings the pressure of the gases within such a combustion chamber has been limited heretofore, however, this pressure usually not exceeding l to 5 atmospheres absolute. Even where in such conventional steam generators the pressure of the generated steam is not in excess of to 40 atmospheres absolute the diiference between the pressure of the steam generated within the steam generating elements or tubes and the pressure of the combustion gases within the combustion chamber is so great that the steam and water confining elements and parts must be made to withstand a high diierential pressure. The casing of the combustion chamber also must be made sufficiently strong to withstand the pressure of the combustion gases in the combustion chamber. The practical limitations heretofore placed upon the pressure at which the combustion gases may be produced within a combustion chamber not only have limited severely the range of pressure available for the production of power from the com bustionrgases in a gas utilizing prime mover but also have prevented the attainment of other improvements in the eiciency of production and utilization of the combustion gases. For example, the efficiency of heat absorption by the generated steam has been limited.

It is an object of the invention to provide apparatus of an` improved construction for generating vapor by the heat of combustion of fuel under pressure in a combustion chamber.

, it is another object of the invention to provide apparatus and a method of operating such apparatus for generation of vapor by the heat of combustion of fuel in a combustion V chamber which will secure advantages in the eciency of operation as well as in the construction of the apparatus and the cost thereof.

It is a further object of the inventionrto provide a. method of operating a power generating plant by utilizing for development of power both the vapor generated bythe heat of the combustion of fuel in a combustion chamber and the combustion gases produced in this combustion chamber which will secure improvement in the eineiency of operation and in the cost of the plant. Y

It is an important underlying feature of the invention that the pressure at which the combustion of the fuel is effected in the combustion chamber is approximately the same and preferably substantially equal to the pressure of the vapor generated in the vapor generating element receiving the heat Vfrom the combustion gases.

According to the invention there is provided in a vapor generator, e. g., a water tube boiler, a pressure resistant casing enclosing a combustion chamber wherein high pressures approximating the steam pressures generated lin said boiler may be maintained, means for supplying fuel tosaid chamber, means for delivering air under pressure into said chamber for combustion of the fuel supplied thereto, vapor generating tubes within said chamber, the air for combustion being injected into said chamber under pressure, at least 5 kilograms per square centimeter, and the pressure of the gases within said chamber outside of said tubes being maintained substantially equal, as' hereinafter described, to the pressure of the vapor produced in said tubes so that stresses of the heated elements of said vapor generator' are limited and only the cool casing is required to withstand high pressures.

Since the casing of the combustion chamber is constructed to confine the combustion gases therein at a pressure approximating the vapor pressure, the differential between vapor pressure and the pressure of the combustion gases within the chamber `which the vapor generating element is required to withstand is small and the Walls of the vapor generating element may constitute merely separating partitions between the combustion gases at the outside of the element and the liquid and vapor within the element. These walls are not subjected to any appreciable mechanical stress and may be made thin and capable of providing a high rate of heat transfer therethrough. Vapor generating elements of this form also readily may be made of any desired shape or cross section suitable for the conditions of the construction and for a high rate of heat transfer from the gases to the liquid and to the generated vaporand to provide for nontortuous gas passages therebetween requiring only a relatively small pressure drop in the gases to insure their flow over the vapor generating elements in heat transferring relation thereto.

Although the casing is required to be constructed so as to withstand internally thereof the full pressure of the combustion gases of a degree approximating or equal to the pressure of the generated vapor, the metal of this casing or shell may be thoroughly protected from the heat of the combustion gases and from Contact therewith so that this metal may be maintained at a temperature which maintains the strength of the metal. To aid in securing the protection of the shell against the heat of the combustion gases it may be lined internally thereof with a refractory material as well as with an insulation layer between the refractory and the metal of the shell. The exterior of the casing is exposed to the atmosphere and its temperature is kept low by transfer to the air of such heat as passes thereto through the refractory lining and insulation.

The vapor generating element or certain of a plurality of such elements are arranged adjacent the wall of the casing or adjacent and within the refractory lining thereof to shield this wall and lining from the radiant heat of the combustion gases as well as from direct contact with the hot gases. The heat directed toward the wall of the shell thus is intercepted and utilized for the generation of the vapor and the shell exposed to the atmosphere exteriorly thereof is maintained at a safe temperature. Since, as above stated, these vapor generating elements are not required to withstand a. high pressure they may be of any desired cross section and shape to suit the arrangement thereof which will insure the requisite heat intercepting relation with respect to the wall of the shell or the refractory lining thereof.

Bythus constructing and arranging the combustion` chamber and the vapor generating element or elements therein it becomes possible to utilize materials ordinarily available for the construction of conventional low pressure vapor gen-- 4 erators for constructing the vapor generator of the invention to generate vapor at pressures of the degree of `atmospheres absolute or higher. Moreover, the combustion gases may be produced by the combustion of fuel within the combustion chamber at temperatures ordinarily developed in the combustion of conventional fuels such as oil, gas, powdered coal or composite or colloidal fuels, and the temperature of the combustion gases after delivering heat to the vapor generating elements for the generation of vapor may become reduced, for example, to a temperature of 500 C. at the gas discharge from the casing. Thus, without exceeding' the temperatures which conventionally used materials may withstand, the gases at such elevated pressure and temperature may be usedl in a gas utilizing prime mover with a high pressure drop and a high temperature drop to the pressure and temperature of the exhaust from the prime mover tothe atmosphere. These gases, however, may be used for other purposes in the development of power or for supplying v heat.

By effecting the combustion of the fuel to pro duce combustion gases athigh pressure the heat released from the fuel is carried by combustion gases of a very high density. The volume of such high density gases is very small as compared with the volume of gases ordinarily produced in conventional combustion chambers adapted for effecting combustion at the relatively low pressures heretofore used. Since the volume of the combustion gases is small the requisite cross section for flow thereof through the gas passages for contact with heating surfaces of the vapor generating elements or other heat transfer elementsv is small and may be made sufficient to produce only a small pressure drop requisite for effecting movement of the gas over such heating surfaces. Moreover, as the mass of the gases per unit of volume is high the heat transfer rate is high and the amount of heating surface necessary for a given capacity,Y that is, a given amount of vapor to be generated and a corresponding amount of combustion gases to be produced, is Small. This` limited amount of required heating surface further limits the pressure drop necessary to produce ow of the gases over the heating surface while securing the'l desired reduction of the temperature of these gases corresponding to the amount of vapor generated from the heat thereof.

For these and other reasons Iwhich will appear from the further description of the invention the method of operating a' vapor generator by effecting combustion of the fuel to produce combustion gases at a pressure approximating the pressure of the generated vapor requires a construction of much reduced size and cost for a given capacity as compared with conventional methods and structures and makes possible not only improved efficiency in the combustion of the fuel but also more efficient utilization of the heat thereof for the generation of the Vapor concomitantly with the production of gases at elevated pressure and temperature. t may be shown that the cost of the auxiliary equipment necessary for compressing the combustion supporting gas, usually air and the cost of operation of this equipment are such that a marked overall improvement is obtained in the eiiiciency and in the economy of operation.

In `accordance with another important feature ofthe invention means are provided for maintaining the pressure of the combustion gases within the combustion chamber and the pressure Y pressed air thereto.

of the .vapor generated in the vapor generatingy element in a predetermined relation to each other Y and preferably substantially equal. Although not so limited this feature will be described in connection With its application to the operation of a steam generator which may be provided with a plurality of tubes arranged Within a combustion chamber, the fuel being burned to produce the combustion gases `under a pressure approximating the steam pressure by supplying air to the combustion chamber' compressed to a pressure approximating the steam pressure.

AThe pressure of the steam generated by the combustion of the fuel varies as the withdrawal of the steam from the tubes and the supply of the heat varies. The pressure of the combustion gases within the chamber varies in accordance to the rate of withdrawal of the combustion gases therefrom and the delivery ofrfuel and com- To maintain the desired predetermined relation of the pressures means are provided for controlling the supply of the fuel to the combustion chamber and concomitantlycontrolling delivery of the air to the chamber against the pressure of the gases Within the chamber. Means also may be provided for controlling the discharge of the steam and of the combustion gases from the generator. Similarly tothe conventional types of control the supply of fuel to the combustion chamber may be regulated so as to maintain the desired pressure of the generated steam. The delivery of the air also may be regulated to supply an amount of airnecessary for combustion of the fuel for generating the steam and concomitantly it may be regulated to maintainV the desiredV relation of the pressure within the combustion chamber with respect to the pressure of the generated steam. j

To accomplish the control of the fuel supply and the delivery of the vcompressed air, in laccordance with a unique aspect of the invention, means responsive both to the pressure of the steam and the pressure of the combustion gases Within the `chamber may be used to adjust or regulate the fuel supply and to adjust or regulate the delivery of the air so as to maintain the requisite combustion and the desired relation of the pressures of the" steam andof the gases within the c ombustion chamber. This means may include a device so constructed and so connected to a space conninfg'the' generated steam and to a space communicating with the combustion chamber as to be actuated by variations from a predetermined difference between thepressure of the steam and the pressure of the combustion gases. The predetermined diierence, or narrow range within which the vapor pressure and the pressure of the combustion gases are permitted to vary with respect to one another, in practice usually will be kept below about 14 pounds per square inch or l kilogram per square centimeter, and sucha variation is encompassed Within the term substantially equal pressures asused herein.

This differential device may be connected to the'means for supplying the fuel and to the means for delivering the air so that as the pressure of the steam increases kand decreases relative to the pressure of the combustion gases the.

.from the combustion chamber.

lcation the differential device may be connectedV decrease and increase, however, being effectedin response to increase and decrease of the pressure of the generated steam relative to the pressure of the `combustion gases within the combustion chamber. to the pressure of the gases within the combustion chamber may be utilized for effecting supplementary delivery of compressed air to the combustion chamber so as to regulate the pressure therein and thereby to cooperate With the device which is responsive to the difference vbe tween the steam pressure and the combustion gas pressure so as to maintain the predetermined relation between these pressures.

In another aspect of the invention the device which is responsive to the variations in the difference between the pressure of the generated steam and the pressurev of the combustion gases within the combustion chamber may be connected to means for controlling the discharge or Withdrawal of the steam from the steam generating elements and to the means for controlling the discharge or withdrawaljof the combustion gases When thus connected the device may be effective to regulate the discharge of the steam and of the combustion gases so as to maintain the pressures thereof respectively in the steam generating structure and in the combustion chamber in the predetermined differential relation. This differential device may be constructed and so connected to these y discharge means as toactuate these means so as toreduce the amount or rate of discharge of the steam and correspondingly to increaseA the amount or rate of discharge of theV combustion gases from theY combustion chamber Whenever the pressure of fthe generated steam reduces below the predetermined relation with respect to the pressure of the combustion gases untilthe predetermined differential relation of these pressures is restored. Whenever the pressure of the generated steam relative to the combustion gas pressure becomes in excess of the predetermined differential the device may actuate the discharge control means to increase the discharge of the steam and to decreasethe discharge of the combustion gases. As will be more clearly under- Y stood from the description of the drawings tov follow the differential control device thus arranged for control'of the discharge of the steam and of the combustion gases from the steam generator of the inventionmay control the flow of the steam and of the gases respectively to steam and gas utilizing prime movers and may cooperate with the governor of one prime mover, for examplethat utilizing the generated steam, so as to control the flow of this steam to this prime Y mover to regulate the speed and deliver the power In this embodiment means responsive` ber may be' regulated in ac'onventio'nal manner by means responsive. to variations in pressure of the generated steam. Such. conventional means ordinarily are `adapted to increase and decrease both the supply of. fuel and of air in response to decrease and increase of the steam pressure. In a particular adaptation of such control this means responsive to variations in the steam pressure may be connected to a fuel feeding de* vice for controlling the operation of this device to increase and decrease the feed of the fuel to the combustion chamber. It also may be connected to means controlling the flow of the air to the combustion chamber or in a particular application it may be connected to a power means which drives a compressor for compressing the combustion air. Such power means may be an internal combustion engine utilizing fuel such as oil `and in such ycase the means responsive to variations in the steam pressure may be connected to a fuel feed pump for controlling the operation of this pump to regulate the feed of the fuel to the internal combustion engine, thereby to regulate the amount of the compressed air delivered to the combustion chamber.

In combination with such means responsive to variations in the pressure of the generated steam and regulating the supply of fuel and delivery of air to the Combustion chamber, the differential device above referred to may be utilized for controlling the discharge of the generated steam from the steam generating elements and the discharge of the combustion gases from the combustion chamber as above described so as to maintain the predetermined relation of the pressures of the steam in the steam generating elements and of the combustion gases in the combustion chamber.

The differential device above generally described may be constructed and may be connec'ted to the steam space and to the combustion chamber so as to be responsive to variations frorn a predetermined difference between the steam pressure and the combustion chamber pressure both for the condition that the pressure of the steam normally is to be maintained somewhat in excess of the pressure of the combustion gases in the combustion chamber and for the condition that the combustion gas pressure is to be maintained somewhat in excess of the steam pressure. If for either condition means are utilized as above described for maintaining the pressure of the gases in the combustion chamber substantially constant it will be understood that the differtntial device may effect r.

control of the fuel supply to regulate the steam pressure or it may control both fuel supply and delivery of air to provide for efficient combustion of the fuel. For either condition as the steam pressure increases relative to the atmos phere it is necessary that the device be connected to the fuel supply so as to reduce the supply of fuel in order to reduce the generation of the steam. As the steam pressure falls the fuel supply must be increased. For the condition that the steam pressure normally is in excess of the combustion gas pressure the difference of pressure between the steam and combuston gases will be increased when the pressure of the steam increases and vice versa. When the pressure of the steam normally is less than the combustion gas pressure the pressure difference will decrease when the steam pressure rises and vice versa.

It will be understood, therefore, that increase of the vapor or 'steam pressure herein referred to as relative to 'the pressure of the combustion gas within the combustion chamber relates to both of the normal conditions above mentioned and that suchY increase, of the steam pressure relative to the combustion gas pressure may correspond to an increase or a decrease of the difference between the pressures. O-n the other hand, decrease of the steam pressure relative to the combustion gas pressure may correspond to a decrease or an increase of the difference between said pressures. AIt will be further understood. that the relationship just described and the manner of connecting the differential ldevice are to be maintained even thou-gh the pressure of the combustion gases, kinstead of being maintained substantially constant, var-ies with variation in the amount and pressure of the air delivered to the combustion chamber or of the gases with'- drawn therefrom.

YOther objects and features of the invention will be understood from the description to follow of the drawings in which:

Fig. 1 is a vertical section of a steam generating apparatus in accordance with the invention showing controlr by the differential device both of the fuel` supply and the, delivery of the combustion supporting air to maintain a. predetermined relation of steam. and gas pressures;

Fig. 2 shows diagrammatically the control of the fuel supply by the differential device, the combustion chamber pressure being maintained substantially constant by control of the pressure ofV the compressed air delivered thereto;

Fig. 3 shows diagrammatically a modification in which thev differential device controls the fuel supply and the delivery of air for combustion, the combustion chamber pressure being maintained substantially constant by a pressure regul'ator controlling supplementary delivery of compressed air;

Fig. 4 shows diagrammatically the steam generator ofthe invention arranged for delivery of the steam to a steam turbine and of the combustion gases to a gas turbine for developing power from the steam and these gases;

Fig. 5 shows a modification of the power plant of Fig. e in which the pressure responsive controls include relays for controllingY an auxiliary or control fluid for operating the fuel supply control means and the air delivery means;

Figs. 6, 'l and 8 are sections taken on lines 6 6, I-l and '8MS respectively of Fig. l;

Fig. 9 shows diagrammatically a somewhat modified arrangement of the steam generating and superheating tubes of Fig. 1 and the course of the water and steam therethrough;

1 Fig. l() is a vertical section of a portion of the headers to which the steam generating tubes of Fig. l are connected;

Fig. l1 shows diagrammatically a modification of the steam generator of Fig. l in which the normal pressure of the combustion gases exceeds the pressure of the generated vapor.

In Fig. l is shown more or less diagrammatically a steam generator or equipressure boiler l which is constructed with an outer casing or shell 3 as a steel cylinder having a hemispherical lower end which maybe forged in one piece. At the upper end of the casing 3 is fitted a hemispherical removable cap E fastened by any suitable means at the flanges 'I and 9 respectively of the casing 3 and the cap V5. At the lower end of the casing a flanged opening l) is provided for the` admission of air and for the insertion of 9 Y the burners II disposedwithin a burner shell I3 carrying a flanged connector I5. This air for combustion may be controlled by hand valve 23 fractory lining 3 I.

and by control of the air compressor about to be described. y

Within the casing 3 is supported a refractory lining 3l). The lower hemispherical end of the casing I3 is provided with a hemispherical re- The cap 5 also is lined with a refractory lining 33. These refractory linings are supported in spaced relation to the casing 3 and the cap 5, this space preferably being lled with insulating material, for example asbestos flock. The refractory lining may be supported by a light metal framework constructed so that the lining may be placed in position or removed from the casing upon removal of the cap 5 and the other parts of the steam generator further Vto be described. The refractory lining and the insulating layer Serve not only to limit the heat which is transmittedto the casing but also to confine the heat within the combustion chamber to improve the combustion.

Because of the high pressure at which the combustion is effected in the steam generator of the invention the volume of the combustion space necessary for the combustion of the fuel for a given capacity is small. The diameter as well as the overall size and weight of the casing 3, therefore, is small. The thickness of the casing 3 need not be excessive safely to withstand the pressure of the combustion gas within the combustion chamber of the degree of or equal to the vatmospheres or more.

steam pressure which may be as high as 120 amount of material sufficient thickness of the refractory lining and of the insulating layer,

moreover, may be provided to keep the temperature of the casing from rising .to the point where the` strength of the metal of the casing would be reduced. IThe construction and dimensions of the gas confining casing or shell, therefore,

Vcorrespond generally to the dimensions of pressure vessels for corresponding pressures rather than to the dimensions necessary for combustion of fuelv in conventionalA combustion chambers. The thickness of the shell need not be such as to allow for the action ofA the heat or the impingement of the hot gases thereon since it is protected by the refractory and insulating materials supported between the material of the shell and the hot combustion gases as well as by the steam generating elements about to be described. For a capacity, for example, of 440,000 pounds of steam per hour at a pressure of v80 atmospheres absolute, the pressure of the combustionlgases being substantially equal to the steam pressure, and burning, for example, pow,- dered coal as fuel, the diameter of the casing of the steam generator may be about 5.5 feet and the length of the casing including the hemispherical ends mayf be about 18.5 feet.

Within the space defined by the refractory lining supported within casing 3 and the cap 5 of Fig. l are disposed the steam generating elements in the form of tubes to which the feed vwater is delivered from a feed pipe 35 controlled Without need for a large ing 33 of the cap 5 to protect this lining and the cap from the direct action of the combustion gases passing from the combustion chamber upwardly through the nested wraps of the economizer and through the discharge pipe 4I fastened by the flange 42 to the cap 5, this discharge being controlled by the gas outlet valve 43.` The lower end of the coil 39 is connected to a ring shaped header 415 extending about the space within the lining 3U adjacent the joint between the flanges 1 and 9 of the casing 3 and the cap 5. The header 45 may be connected to the lowerrnost wrap of the economizer coil 39 at one or more places to insure proper delivery of the feed water heated in the economizer coil to the header 45 for distribution to the steam generating tubes. Y

Thesteam generating tubes comprise the legs 41 which extend vertically downward from the header 45 along the inner face ofthe refractory lining and form loops 49 atk the lower end thereof adjacent the burner II as shown in Figs. 1 and 6 to intercept the heat and to protect the refractory lining and the Vertical wall of casing .3 as well as the lower hemispherical end of the casing. From the loops 49 the tubes again proceed upwardly along the face of the refractory lining 30 and bend at 5I to pass across the combustion space to the opposite side thereof, thence to proceed upwardly as legs 53 to the ring shaped header 55 disposed within and concentric with the header 45. As shown in Figs. 1 and 8 concentrically disposed with respect to the headers and 55 are headers 55, 51, 58, 59, SI1, 6I and 62.

.By the U-shaped connector 53 shown to enlarged These connections are made at a plurality of points about the central axis of the casing 3. At the lower side of these headers steam generating tubes 65 of U or hairpin shape with the bends thereof disposed downwardly are connected to the headers so as to connect together respectively headers and 51, 58 and 59, 55 and 6I. These steam generating tubes 55 are disposed about the axis ofthe casingrin the manner shown in the horizontal cross section in Fig. 7. As shown in Fig; '1 the vertical legs of the tubes 65 are disposed in staggered relation at opposite sides of the radial lines which extend from the axis of the casing generally toward the legs 41 of the tubes which are disposed adjacent the refractory lining. Having regard to the connections as just described of the U-shaped connectors 63 and to the connections of the upper ends of the U-shaped steam generating tubes 55 to the headers it will be noted that the water which is delivered to the header 45 is directed downwardly through the legs 41 and again upwardly and across the combustion chamber and continues upwardly in the legs 53 to the header 55, thence in rsuccession through the tubes 65 and the consecutively num?- bered headers 56 to 62. The innermost leg of the steam generating tube 65 is connected to the header 6I which is connected by the U-connector to the innermost ring header 52.

To the lower side of the header 32 in the manner shown for the left hand header of the detail section in Fig. 10 the first vertically disposed leg 51 of the super-heater is connected, the lower end of the openings 89.

enzimas header 69, Fig. 1. Also connected to the header 69 are two riser legs 10 of the superheater which at their lupper ends are connected to a central superheated steam collector 'il to which the outlet pipe "I3 is connected, this pipe passing through an opening in the refractory lining 33 and a registering opening in the cap 5 to which the pipe 'I3 is attached by means of flange l5, suitable packing 'I'I being provided about the pipe i3 to provide for expansion and contraction. 'I9 is provided in the outlet pipe 13 for control of the outflow of superheated steam from the steam generator.

As shown in Fig. the headers 55 and 5i, Sie and 59, 6|! and 6| may be formed as compartments in respective integral headers 89 divided Vinto these compartments by partition 8 l, the tubes 65, 61 and Iii being connected at the vrespective sides of the partitions 8|v having regard to the connection of the U connectors 3 whichprovide for Vflow of the water or steam from one header to the next, lthat is, between the respective compartments in the adjacent headers to secure a series flow throughsteam generating and superheating tubes. The U connectors S3 are held in .place by yoke bars 33 which pass through opere ings in upwardly extending lugs 84 formed in the embodiment oi Fig. 10 as extensions of the partitions 8|. Tapped in the bars S3 and extending therethrough are screws 35 for engaging plates 81 vwhich are formed as closures for openings 39 in the upper face of the headers Sii. Each compartment lis provided with an opening to provide access to the tubes for rolling them into the lower walls of the headers 8d land for cleaning of the tubes. Ity will be understood that the screws 85 may be screwed downwardly to press the plates :8.1 downwardly7 into closing engagement with the headers 80, the reaction being taken by the lugs .84 through the bars 83 to secure a tight closure This construction provides for disconnecting the headers so that they may be removed together with the tubes which are attached thereto.

It will be understood from the above description and consideration more particularly Figs. 1, 6, 8 and 10 that by disconnecting at the re spective flanges the external steam and gas outlet pipes 4| and 'I3 and the feed supply pipe 35 the cap 5 may be removed in one piece. The .economizer 35 and the headers 45 and 55 to 62 inclusive are supported so that the economizer first may be removed and then the other boiler lelements, such as the headers and the steam generating tubes connected thereto, or the whole assembly of these elements within the lrefractory 'lining may be removed as a unit.

In order that the drop in temperature of the `hot gases as they Apass through the nest oi tubes within the gas space above the combustion chamber proper as shown in Fig. 1 shall be substantiallythe same/at the center oi the chamber as at the periphery, although the temperature of the ,steam n the superheater is different from that .of the water 4flowingirom the economizer through the outermost tubes M .and diierent from the temperature oi the steam and water mixture conn ned Within the intermediate steam generating tubes `Iii, the cross section Vof the gas passages between these several tubes decreases in the di rection from the periphery of the chamber toward the center thereof as may be seen Ain Fig. "7. As shown .in Fig. 9 a damper 89 movable in the direction along the axis of the combustion chamber may be provided to cooperate with the. ,cen-

A valve p trai Jbox'lil to control the flow of the gases .over

the superheater section constituted bythe tubes 'I' for regulating the temperature of the superheated steam.

In order to secure control of the operation of the steam generator of Fig. 1 and to maintain the desired difference between the steam pressure and the pressure of the combustion gases within the casing 2% as above generally described, a differential pressure device |09 is provided having a cylinder ISI within which is movable a piston 93 between the upper side of which and the upper head of the cylinder IIlI is positioned a compression spring |65. The space above piston I 03 ccmmunicates through pipe |01 with the gas space within the casing 3 'by beingY connected to the outlet pipe 4I below Vthe valve G3. The connection of the pipe I'I may be made at this place in view of the low pressure drop between the pressure of the combustion gases within the combustion chamber I2 and the pressure of the gases at the discharge pipe 4 I, this low pressure drop being possible because of the limited amount of heating surface and its arrangement and construction in View of the high density of the combustion gases as above described. The pipe Il, however, may be connected at some other place upon Athe casing 3 in order to make the piston V|03 responsive to the combustion chamber pressure or to the pressure of the gases at some other point inthe flow thereof from the burners to the gas outlet 4i.

The space beneath the piston |03 in the cylinder IBI is connected by pipe |09 in the embodiment shown in Fig. 1 to a wrap or convolution of the economizer coil 39. As the water is delivered in series through the economizer to the steam generating `tubes 65 and the economizer tubes may be made to provide a substantial area for now of the water therethrough, the pressure within the economizer may be substantially the same as or not greatly different from the pressure of the generated steam. The pipe |09, however, may be connected elsewhere to the steam space within the steam generating structure or to some space within a header or other part which is in communication with the space in which the steam is generated or is superheated so as to substantially bring upon the underside of the piston |03 the pressure of the generated steam.

It will be understood inthe particular embodiment shown in Fig. 1 that the pressure of the steam may be somewhat higher than the pressure of the combustion gases confined within the casing 3, the difference between these pressures correspond-ing substantially to the compression of the spring |65. It will be understood also in this embodiment that as the steam pressure rises relative to the pressure of the gases `within the combustion chamber the difference between these pressures, that is, the excess of the steam pressure over the gas pressure, increases and the spring |05 is compressed with concomitant movement of the piston |93 upwardly in Fig. 1. If the steam pressure, on the other hand, falls the difference between the pressures, that is the excess of the steam pressure over the gas pressure, is reduced and the piston ID3 moves downwardly until the pressure of the steam acting on the piston ID3 balances the pressure of the gas and the compression of the spring acting at the upper side of the piston |93.

Ii, on the other hand, the normal condition of operation desired to be secured is that the gas pressure within the combustion chamber or the rgas space within the casing 3 shall exceed somewhat the pressure of the generated steam the spring may be placed at the under side of the piston |03, as shown in Fig. 11, the spring thus balancing the excess of the gas pressure over the steam pressure brought upon the under side of the piston |03. In such case, when the pressure of the steam rises relative to the gas pressure the difference between the pressures, that is, the excess of the gas pressure over the steam pressure will decrease. Nevertheless, the piston |03 will move upwardly being assisted by the spring |05 until the balance is restored.` If, on

the other hand, the pressure of the steam falls' relative to the gas pressurey the difference between these pressures will increase but the piston will move downwardly in Fgpll, the gas pressure compressing the spring somewhat until the balance of the pressures acting on the piston |03 Y is reached.

It will be apparent, therefore, that in both cases where the steam pressure rises relative to the gas pressure the piston is moved upwardly and where the steam pressure falls relative to the gas pressure the piston moves downwardly. If by means about to be described the gas pressure within the combustion space is maintained constant or substantially so the diierential device as shown in Figs. 1 and 11 is responsive to variations of the steam pressure relative to this constant gas pressure. On the other hand, if both the gas and the steam pressure are subject to variation the device, nevertheless, is responsive to variations of the pressure difference from a predetermined difference betweenV these pressures, these variations being utilized in the manner now to be described to control the pressures of the generated steam and of the combustion gases within the casing 3 so as to maintain substantially constant the diierence between these pressures. The advantages above referred to with respect to the structure and the economy of operation of the steam generator of the invention thereby may be insured.

In the embodiment of Fig. 1 the piston |03 is connected by the vertical rod to a three arm lever H3, this rod being connectedl at the outer end of the right hand arm Il of the lever ||3 with respect to a stud or shaft ||5 upon which the lever ||3 pivots. The left hand arm ||6 of the lever ||3 is connected by means of a link to the stem of a valve ||9 connected in the fuel line Il, the valve disc of this valve as shown in dotted outline being arranged to move upwardly with respect to the valve seat |2| to open this valve. Extending downwardly from the pivotal stud ||5 the lever ||3 is provided with an arm |23 connected by connecting link |25 to the driver |2'| of the air compressor |29, this air compressor being connected to the pipe 2| for delivery of the compressed air therefrom to the combustion chamber |2. The connections of the rod |25 to the driver |27 and between the driver and the air compressor |20 are shown diagrammatically. The driver may be a motor or a prime -mover of suitable type and the air compressor may be of conventional type for supplying air Aunder a pressure of the same degree as the steam pressure to be generated, this compressor being provided with conventional regulating means for maintaining a suitablev outlet pressure and constructed for delivery of the compressed air in the proper volume to supply the combustion chamber for combustion of the fuel therein having regard to the outow of the combustion gases 'withdrawn from the combustion chamber through thefoutlet pipe 5| as controlled by valve 43 or by the controls at the point of use.

It now will be understood that in the embodiment of Fig. 1 an increase of the steam pressure relative to the pressure of the gases in the combustion chamber eifectin-g an upward movement of the piston |03 produces counterolockwise rotation of the lever H3 on its stud H5 to close the valve disc |20 upon the seat |2l, thus to reduce or to stop flow of the fuel through the pipe to the burners Correspondingly such upward movement of the piston |03 produces movement toward the right or the connecting link |25. The link |25 is so connected to the driver of the compressor as to increase the speed of this driver and of the compressor or otherwise to control the operation of the compressor so as to increase the delivery of the compressed air or the pressure thereof through the pipe 2| to the combustion space l2 for combustion of the fuel delivered to the burners The reduction in the amount of fuel delivered to the burners l reduces the amount of heat released in the combustion space I2 thereby to reduce the pressure of the generated steam. The increase in the delivery of the compressed air to the combustion space or the pressure thereof increases the pressure of the gases within this combustion space. The controls of the fuel supply and of the delivery of the air in this manner cooperate to restore the relation of the steam Vpressure to the combustion gas pressure.

If, in theembodiment of Fig. 1,where the steam pressure is desired to be somewhat in excess of the gas pressure, because of variation in the outflow or in the generation of the gases of combustion or for other reason, the pressure of the gases within the casing 3 should decrease relative to the steam pressure, thereby increasing the diierence between these' pressures, the piston |03 in/this supply of fuel and the operation of the compressor will be controlled so as to increase the delivery of the compressed air to the combustion space or its pressure It will be clear also, on the other hand, that if the pressure of the steamis reduced relative to the gas pressure, either by reduction of the steam pressure or by increase of the gas pressure, opposite movement of the piston |03 will be produced with corresponding opening of the fuel valve |20 and decrease in the delivery of the compressed air or its pressure until the predetermined pressure diierence within the casing 3 is restored. It will be understood that the device as schematically shown in Fig. l operates to restore the relation of the steam and gas pressures within the casing 3 for any variation in the steam pressure or of the gas 'pressure which produces an increase of the steam pressure relative to the'gas pressure or a decrease of the steam pressure relative to the gas pressure.

It will be apparent also, where the gas pressure to be maintained within the combustion chamber is in excess of the steam pressure to be generated in the steam generator, that the differential device arranged as shown in Fig. l1 when its piston |03 is connectedto the valve l i9 and to the driver of the air compressor by the rod iii, lever H3 andthe link connections and |25 as shown in Fig. 1 will be effective to decrease and increase the supply of the fuel to the burners and concomitantly to increase and decrease the delivery of the Vcompressed air to the combustion space,

thereby to control the pressures of the generated Vsteam and of the combustion gases within the casing to maintain the desired predetermined -pressure difference according as the pressure of being diagrammatically represented in serpentine form, the feed water being delivered thereto through pipe 35. The steam is discharged through the pipe 13. As shown in Fig. 2 the differential device I ESG is connected in the same manner as in Fig. l to the gas space within casing 3 through pipe IS'I and to the steam space through pipe It.y The rod I! I connected to the piston HB3 is connected to a double arm lever M in this ernbodiment. rIhis lever is pivoted upon a stud IM,

the rod I I I being connected to its right hand arm |42. The left hand arm 53 of lever ist is connected by the link It to the stem of valve I I9 the Valve disc IZ of which in its lowermost position rests on the seat I2! within the valve body H9 connected in the fuel supply line il the same as in Fig. l. In Fig. 2 the burner Ii is diagrammatically shown and the compressed air is delivered to the combustion space within casing 3 through the pipe 2i from the compressor I29 similarly to Fig. l. In Fig. 2 the driver of the air compressor is not shown and no connection is provided between the rod III and the driver of the compressor or to any flow controlling means associated with the compressor. In this embodiment a receiver Uil is provided connected to the discharge pipe 2i or" the compressor to receive and store the compressed air in the conventional manner. The compressor also may be provided with 4conventional control means, such as an unloading device responsive to the pressure in the receiver IM and connected also to means for driving the compressor, for example the throttle valve of an engine connected to the compressor for driving the compressor, so as always to maintain within the receiver a predetermined pressure. The pipe 2l may be of sufficient size, having regard to the length thereof and to other iiow conditions, so that the pressure maintained in the receiver is substantially the same as or in the predetermined relation to the pressure within the combustion chamber. It will be understood, therefore, that the compressor cooperating with this receiver 41 may be utilised in the conventional manner to maintain a predetermined substantially constant pressure of the combustion gases within the combustion space and within the casing 3. When such contant or substantially constant pressure .of the combustion gases is maintainel within the casing 3 the differential device as shown in Fig. 2 operates to control the supply of the fuel to the combustion space and, therefore, the generation of the steam in response to variations in the pressure of the steam relative to this substantially constant pressure of the combustion gases. In the embodiment of Fig. 2, a predetermined diierence, that is, an excess of the steam pressure over the gas pressure may be maintained by such control of the fuel supply to the burners II. The construction of the differ- "16 ential'device of Fig. 1i, however, may be vutilized in the embodiment or Fig. 2 when it isdesired to maintain the combustion gas pressure somewhat in excess of the steam pressure, the rod Iii of Fig. 1l being connected to the lever MII in the manner shown in Fig. 2.

In Fig. 3 the steam generawsg tubes 61E are also ci serpentine form, the feed cater being delivered thereto through the pipe and the steam being discharged therefrom through pipe 53. In this embodiment Ythe differential device Il is corn ected to the gas space through pipe itil and to the steam space through pipe it@ as in Figs. l and 2, the pressure oi the steam in this embodiment also being normally somewhat in excess oi' the pressure gas in the combustion chamber. The rod iii is connected at its lower end to a stiff arm Ii to the opposite ends or" which respectively are connected the stems i513 and E of the fuel supply valve i It and ci the valve l? for controlling the delivery of the compressed air through the pipe 2i to the combustion chamlier. As shown in Fig. 3' the valves are oi such construction and arranged in relation to the stiii arm E55 that upward and downward movement of the rod iii respectively effect closing and opening movements of both the valve disc I2l-3 oi the valve iis andof the valve disc it* of the valve ii in response to increase and Ydecrease in the steam pressure relative to the gas pressure. `t thus will be apparent that an increase of the steam pressure relative to the gas pressure is effective to decrease the supply of iuel to the burner .ii through the pipe il and simultanes ously to decrease the delivery of the compressed air to the combustion chamber through the pipe 2i so as to supply the air requisite for the co i-- bustion of the decreased amount of fuel. Correspondingly when the steam pressure decreases relative to the gas pressure the control device oi Fig. 3 is effective to increase the supply or" fuel to the burner ii and correspondingly to increase the flow oi compressed airthrough pipe 2l to the combustion chamber.

In order to maintain a predetermined relation between the pressure of the gas within the combustion chamber and the steam pressure desired for operation of the steam generator of the invention means are provided in the embodiment of Fig. 3 for regulating the delivery of the air in response to variations in the pressure within lthe combustion chamber. In a bypass pipe lei about the valve I5? is connected a valve M33 of the pressure regulating type provided with a diaphragm within the cell EEG responsive through pipe ii to the pressure in the pipe 2E. The pipe 2i may be of such size that the pressure to which Vthe diaphragm of the valve 53 is subjected is substantially that of the combustion chamber or the pipe E may be connected directly tothe combustion chamber. The diaphragm actuates the valve stem of the valve |53 to ei'ect now restricting movement of the valve disc i upon an 'increase-in the pressure in the combustion `chamber'and will close the valve when the corn-- bustion chamber pressureequals or is in excess of a desired predetermined pressure above atmospheric pressure. Upon reduction of this combustion chamber pressure below the desired pressure opening movement of the valve disc it? effected by bias means such as a spring Hi8 as in conventional pressure regulating devices to increase the now.

The condition may arise that the delivery of the compressed air from a compressor through 17 the pipe 2| connected thereto under the control of the valve |57 is inl an amount which, although sucient for the eiicient combustion of the fuel delivered to the burner II 'under the control of the valve H9, and to maintain or increase the steam pressure, may be insufficient to maintain the pressure of the gases in the combustionchamber?. requisite for the predetermined diiference of pressure between the pressure of steam and gases tov which the device Fig: 3, is responsive. In such event sufficient air is delivered through byn pass ii and the control valve E33 to restore and maintain the desired predetermined pressure in the combustion chamber. Thus, if the condition occurs that the pressure of the steam falls relative to the pressure of the combustion gases within the combustion chamber and both the valve discs |253 and |i;| are moved from or further Vfrom their seats in response to the differential device |03 to increasev the supply of fuel and the p flow of the compressed air and to increase the steam generation and the pressure of the generated steam, the pressure within the comb tion chamber may be maintained up to the desire-:l pressure or may tend to be restored to the desired pressure by delivery of additional air through the bypass valve |63 if the flow through valve 59 is'insuiiicient. If, on the contrary, the pressure of the steam rises relative to the combustion 'chamber pressure the valve discs 23 andv |59 will move toward their seats to reduce both the supply of fuel and the delivery of the compressed air to the combustion chamber. Any such re duction of the compressed air delivery which causes the pressure within the combustion chambery to fall bel-ov; vthe desired predetermined Ipressure will cause the valve disc l? to -move fromits seat to supply additional air-through the bypass to restore the pressure within the com bustion chamber to the desired pressure. `Correspondingly if, due to increased withdrawal of the combustion gases from the casing 3 through the 'discharge pipe ci or for other reason, the pressure within the combustion chamber tends to fall relative to the steam pressure the diierential device led acts to produce closing movement of the valve discs |253 and |59 to reduce the supply of fuel and of combustion air sc as to reduce the pressure of the steam to maintain a predetermined diiferential. The valve 63, however, will prevent undue reduction of the combustion chamber pressure by opening to deliver Vadditional compressed air to the combustion chamber to restore this pressure to the desired predetermined pressure. IThus the `valve serves in cooperation with the valves -HQ 'and i5? to maintain not only a predete-rininedpressure labove atmosphere within the combustion chamber but the predetermined difference between the pressure of the steam and of the combustion gases within the casing 3. v

vIn Fig. 4 is shown an embodiment of the invention which utilizes for control of the fuel and air supply a conventional device responsive to the steam pressure. yIn this embodiment the steam generating tubes E5 also are shown diagrammatically as of serpentine form, thefeed water being delivered thereto through the pinel 35 and the steam being discharged through pipe 'i3 controlled by the valve 7S. Gases are discharged from'the casing 3 through pipe il controlled by the valve' 43..- f

The device for controlling the combustion within the combustion chamber comprises a cylinder having a piston |l6-movable therein. The

lil

space above the piston |76 is connected by the pipe Il? to the steam outlet pipe 'i3 so that the pressure of the generated steam is brought upon the upper face of the piston ll. At the under side of the piston |75 is a spring V39 compressed upon the increase "of the steam pressure and effective to move the piston i'i upward upon reduction of the steam pressure. Increase and decrease of the steam pressure produces respectively downward and upward movement of the rod i8 To this rod is connected the horizontally extending arm of a bell crank lever |83 the downwardlyextending arm of which is connected to the stem of the valve |65 to move the valve disc 85 of this valve toward its seat |87 upon downward movement of rod lill, thereby to decrease the flow of the fuel through the pipe il to the burner Il. Downward movement of the rod I8| also effects movement of the bell crank |83 the horizontally extending arm of which is connected to the rod i8! so that the downwardly extending arm of this bell crank lever connected to the stem of the valve 19| moves the valve disc |92 toward the valve seat |93, thereby to reduce the supply of fuel through the pipe IQE to an internal combustion engine or a gas engine |91. The piston E99 of this engine in the embodiment of Fig. 4 is connected byA the piston rod 260 to the piston 29| of an air compressor 203. The air delivery pipe 2| connects this compressor to the combustion space within the casing 3 of the steam generator as in the embodiments previously f decreased, thereby decreasing the delivery of the compressed air to the combustion chamber simultaneously with the decrease of the supply of fuel to the combustion chamber and decrease in the heat release. Conversely upon decrease of the steam pressure the piston |76 is moved upwardly and the supply of the fuel to the combustion chamber and to the prime mover |91 are increased to increase ythe release of heat in the combustion chamber.

As shown-in Fig. 4 the steam generatedin the steam generating tubes 55 is delivered by pipe i3 through valve le and through a pipe 205 to a steam turbine 2&7 for'developing power therefrom. This turbine is controlled by a governor 2439 actuating the governor valve 2|| to control the speed of the turbine in response to variations in the speed and of load in the 'conventional manner. The gases discharged from the gas space within the casing 3 of the Steam generator are delivered through the valve 43 and the pipe 2|3 to a gas turbine 2|5 for developing power therefrom. The rotor of this turbine is mounted on the same shaft as the rotor of the steam turbine 2M. In the embodiment of Fig. 4 no governor and governor valve is provided in the gas turbine 2|5 for control of the combustion gases delivered thereto under pressure from the space within the casing 3. The two fluids, vhowever, namely steam and combustion gases, under pressure of like degree or at equal pressures are delivered to the respective turbines for development of power upon the same shaft in cooperation with each other by expansion of the steam and the gases in the respective turbines. The speed of the shaft for a given load thereon will depend upon the combined effort induced thereon by the two fluids.

I In order Kto control the operation of the gas turbine 2|5 in proper relation to the operation of the steam turbine in the embodiment of Fig.

l4 a diiferential device 22@ is provided which comsimilari*- through i e 225 connection is estab- J D D lished between the space beneath the piston 22| and the gas delivery pipe 2 i 3 so that the pressure at the under face of the piston is substantially that of the gases discharged from the space within the casing of the steam generator. The size of the pipes and connections and the length thereof in Fig. 4 are not signiiicant, the drawing being diagrammatic. in a practical embodiment the differential device may Vbe suitably located and the connections may be made so as to avoid under pressure drop. increase and decrease f the generated steam pressure relative to the gas iressure developed in the combustion chamber, therefore, is effective to move the piston 22| downwardly and upwardly.

The piston rod 222 of the device 22S extends outwardly of the cylinder at the upper and lower ends thereof. The upper end of the rod 222 is connected to the valve disc 22? or a valve 22S connected in the steam delivery pipe 265, the lower end of rod 222 being connected to the valve disc 22? olf a valve connected in the steam delivery pipe 2dr?. The lower end of rod 222 is connected to Valve dise 22| of a valve 233- connected in the pipe 2l3 delivering the combustion gases to the gas turbine 2|5. rThe valves 229 and 233 and their valve discs and seats are so arranged in relation to the rod that upward movement of the piston 22i effects closing movement of the steam control valve disc 221 and opening movement of the gas control valve disc 23|. Downward rnc-vement of the piston 22| effects opening movement of the steam control valve disc 221 and closing movement of the gas control valve disc 123|.

It will be understood, therefore, that as the steam pressure rises in the steam generating tubes and in the delivery pipe 225 opening movement of the valve disc 221 will be eiected and oorrespondingly closing movement of the gas control valve disc 23|. rihis operation will provide for increased flow of the steam through the pipe 265 to the turbine 2S? and will decrease the now of the combustion gases through the pipe 2|3 to the gas turbine 2 i5. Such operation will tend to increase the speed of the steam turbine and the power output thereof and to decrease the speed of the gas turbine and the power output thereof. The speed of both turbines, however, is the same as they drive the same shaft. The governor 2539 controlling the supply of steam to the steam turbine tends to regulate the speed in response to variations in the load. If under a given load the speed is too low, for the conditions of pres-- sure which have just been stated the increased delivery of the steam through the valve 229 will tend to increase the speed to supply the power demand upon the turbines. Since the power delivered by the gas turbine is reduced, the governor 2525 will operate to permit the additional steam supplied through the valve 229 to flow through the governor valve 2li to the steam turbine iil to maintain the speed and the power delivery of the combined turbine unit. The action of the differential device 22 upon the valve discs 222 lll and 23 I however, will have been effective for restoring the proper differential between the pressure of the steam generated within the steam generating tubes and the pressure of the combustion gases within the casing 3 by increasing the outflow of the generated steam when the steam pressure increases and concomitantly reducing the outflow of the gases from the combustion chamber.

If,.on the contrary, the pressure of the steam generated in the steam generating tubes falls relative to the gas pressure within the casing 3, the pressure at the under side of the piston 22i exceeds the pressure at the upper side of this piston and upward movement of the piston rod 222 is effected with closing movement of the valve disc 221 and opening movement of the valve disc 23|. By such operation the delivery of the steam from the steam generator to the steam turbine 231 is reduced and the delivery of the gases to the gas turbine 2I5 is increased. Such throttling of the steam will increase the Vpressure within the steam generating tubes 55 and such increased flow of the gases decrease the pressure within the combustion chamber so as to maintain the desired relation between the pressure of the steam and of the gases. Such reduction of the steam delivered to the turbine 221 will tend to reduce the speed of the steam turbine and the power delivered thereby. The increase of the flow of the gases to the gas turbine, however, will increase the speed thereof and of the combined unit to maintain the speed thereof and the delivery oi power.

In the embodiment of Fig. 4 the steam pressure responsive means |15 and the differential device 226 and the connections thereto are shown in simple diagrammatic form for ease of explanation of the principle of operation. ln order to avoid hunting and to secure smoothness of control and the desired degree of regulation it is desirable or necessary to provide additional devices and relays. In Fig. 5 is shown a system of controls for this purpose for effecting control of the supply of fuel to the combustion chamber and the delivery thereto of air at the requisite pressure. YIn Fig. 5 certain of the parts like those of Fig. 4 have reference numerals corresponding to those of Fig. 4.

In Fig. 5 the device |15 which is responsive to the pressure of the steam is connected through pipe |11 to the pipe 295 which delivers steam from the steam generator to the steam turbine 201 so that the pressure of the generated steam is brought upon the upper face of the piston |15 of the device |15 in opposition to spring |12 in the same manner as shown in Fig. 4. As in Fig. 4 the steam pressure responsive device 425 `is operatively connected to the means for supplying the fuel to the burner and to the means for supplying fuel to the internal combustion origines which drive the compressor for delivering the compressed air to the combustion chamber. The piston |16, however, instead of being connected directly to the rod |34 as in Fig. 4 is connected through a relay about to be described, the rod |24 being connected to two sets of fuel pumps 'for controlling these pumps respectively to control the fuel supplied to the combustion chamber and the fuel supplied to the internal combustion engines.

The piston |16 is connected by piston rod 24| to a transverse bar 243 carried at the lower end of the piston rod 24| so that upward and downward movement of vthe piston He effects upward 21? and downward movement of the bar 233. Beneath the bar 2113 are arranged four valve boxes 245, 241, 249 and 25|. The valve boxes 245 and 241.9 are provided with seats so formed therein that valve discs 253 and 251 respectively therein both kmove upwardly to closed position, of the valves. In the boxes 221 and 25| the. seats are formed so that the valve discs 255 and 259move downwardly to closed position. The stems 26|, 263, 235 and 261 respectively of the vvalve discs 253, 255, 251 and 259 pass upwardly through suitable stuliing boxes (not shown) in the. top walls of the boxes 245, 241, 249, 25| and through corresponding holes in the bar 2133 in slidingrelation to this bar. These valve stems carry flanges 233 at their upper endsand beneath the bar 243 flanges 21|. Between the flanges 259 of the valve stems 25|, 235 and the bar 223 compression springs 213 are provided which bias these valve stems upwardly with respect to the bar 243to bring the flanges 21| thereof against the under face of this bar. Between the flanges 21! of the valve stems 253 and 231 and the under face of the bar 243 springs 215 are provided which bias the stems 233 and 231 downwardly relative to the bar to bring the flanges 269 into engagement with the upper face of the bar 253.

In the position shown in Fig. 5, thev piston |16 being somewhat below the mid-position in the cylinder E15 bar 253 compresses the springs 215 to close the valves 255 and 259, the bar 223 having moved somewhat away from the flanges 269 of the valve stems 263 and 251. The springs 213 of 'the valve stems 2M and 255, however, have expanded to move the flanges 21| of these valve stems upwardly into contact with the bar 243, the bar 243 acting as a unit with the flanges 21| and the valve stems 25E and 265 and springs 213 and ilanges 269 to hold the valves 253 and 251 downwardly from their seats. downward movement of the piston |13 will effect further compression of the springs 215, further downward movement of the stems 253 and 231 not being possible. Such further downward movement of the stems 28|, 255 and of the valves 253, 251, however, is possible from the position shown in Fig'. 5. Upon upward movement of the piston |16 from the positionV of Fig. 5 the valves 253 and 251 first will move upwardly into contact with their seats and thereafter the springs 213 will be compressed by the bar 2il3. Concomitantly upward movement of the bar 25,3 first will effect expansion of the springs 215 until the bar 243 makes contact with the flanges 239. of the stems 233, 251. Thereafter the valves 255, 253 will be lifted from their seats.'

An auxiliary control fluid, such as compressed air, may be delivered to the relay through pipe 211.` For the position of the piston E15 as shown in Fig. 5 this compressed control air will flow thro-ugh the open valve 251 of the box 223 and outwardly through the pipe 219 connected by a T branch to boxes 242 and 25|. Flow is prevented into the box 25| since the valve 259 is closed. The pressure delivered through the pipe `213 will lopen' check valve 28| in the head of an operating cylinder 233 to bring the pressurerof lthe control air upon the piston 281i to ywhiclfi the rod |S| is connected. Such pressure Further check N be discharged through this box and through the sion the piston rods of these pumps.

zontallyr extending rod 351 also is continued to y exhaust pipe 2139.

When upon reduction of the steam pressureV the piston |15l in the steam pressure responsive device |15 moves'upwardly, being impelled by the spring |19 the bar 253 moves upwardly and closes the valves 253 and 251 and thereafter opens the valves 255 and-253. control air then passes from pipe 211 into the box 241 through the valve 255, now open, and into the pipe 281, being prevented from entering the box 225 since the valve 253 is closed. This brings the pressure upon the check valve 235 to close this check valve in the lowerrend of the cylinder 23.3 and upon check valve 29i to open this check4 valve to admit the control air to the under side of the piston235, thereby to effect upward movement thereof and ofthe rod 18|. As the valve 251 is now closed the compressed. control air is prevented from entering box 2139 and the air previously admitted to the space above the piston 22d may .pass out through the check valve 293 conconiitantly with the closing of the check valve 28 and through pipe 219 and the valve 259 now open in the box 25| to be exhausted through pipe 295.v

It will be apparenu'therefcre, that the rod |84 is moved downwardly with increase of the steam pressure exerted upon the upper face of the piston |13 and is moved upwardly upon reduction ofjthis pressure in a manner similar to the rod ll but with a difference of action which will be described hereinafter.

`In theembodiment of Fig. 5 the rod lSl is connected by a bell crank lever 335 to a horizontally extending rod 391 which is connected to means for controlling the discharge of the fuel feed pumps 339 the pistonsor" which are actuated from a cam shaft 3| l having cams 3|2 thereon for mechanically engaging succes- The horithe'left for actuating the means for controlling the delivery of fuel from the pumps 3|3 for feeding the fuel to the burner of the steamV generator The pistons of these pumps are actuated by cams 3|5 carried on cam shaft 3|5. The fuel discharged from the pumps 333 is carried through the pipes 3|1 'to cylinders 3|9, 32|., 323 and 325 of internal combustion engines the pistons of which aredirectly connected to the pistons of air compressors 321,325, 33|, 333. The compressor 321 is utilized for compressing the-air for combustion of the fuel in the internal combustion engine cylinders, being delivered thereto through the pipe 335. The compressor cylinder323 is a low pressure cylinder of a three-1 stage compressor, the air compressed therein being delivered through pipe Y331 to the intermediate stage cylinder 33|. The air compressed in the intermediate stage cylinder 3.3i is deliveredtthrough the pipe 333 to the high pressure cylinder 333 from which it is discharged through` pipe 339 to the burner housing of the steam generator l for delivery within the casing 3 thereof Vfor combustion in the combustion chamberof the fuelv supplied to the burner il.

In the embodiment of Fig. 5, if the pressure of the steam generated in .the steamgenerating The compressed 27 spherical end of the refractory lining 3i when solid fuels are used, this removal being effected through pipe le controlled by valve i5.

As shown in Fig. 9, instead of all of the steam generating tubes being oi hairpin form as are the tubes certain of these tubes may be constructed by the assembly ci tubes t3 connected to a header at the lov-Jer end thereof in the same manner as are the tubes @i and of the superheater connected to header Preferably in the equipressure steam generator of the invention the wate-l` to be evaporated is circulated through steam generating tubes under forced circulation. While in the embodiment shown in the drawings this forced circulation is represented as a single passage in succession through the various sections of the heating surface, that is, through the economiser7 the several steam generating tubes in succession and through the superheater, other types of steam generating structure may be utilized in which forced recirculation of the water within the structure is provided.

Within the scope of the invention also the struc-tures which have been described in connection with the drawings for the generation of steam and for the development of power therefrom and for the production of combustion gases at high pressure and the develop-ment of power therefrom may be utilized for the generation of vapor from other liquids, such as mercury, liquid hydrocarbons, etc. The apparatus and method of operating to maintain equi-pressure conditions lend themselves to use in heating a wide variety of vaporizable liquids as well as gaseous iiuids. Various adaptations and modifications of the structure different from those described in connection with the drawings may beutilized for the generation of vapor and the production of combustion gases at a pressure of the same degree or equal to the pressure of the generated vapor and for the control of the operation to maintain the predetermined relation of pressures of vapor` and gas. Such variations and modifications are intended to be comprehended within the scope of the appended claims.

This application is a continuation in part of my application Serial No. 472,217, led January 13, 194.3, now abandoned.

I claim:

1. In a vapor generator, a pressure resistant casing enclosing a combustion chamber wherein high pressures approximating the vapor pressures generated in said generator may be maintained, means for supplying fuel to said chamber, means for delivering a combustion supporting gas into said chamber under a pressure of at least 5 kilograms per square centimeter for combustion of ,the fuel supplied thereto, vapor generating elements within said chamber, and means responsive to variations of the vapor pressure generated within said vapor generating element relative to the pressure oi the combustion gases within said chamber for varying the flow oi gases through said chamber for maintaining the pressure of the gases within said chamber outside said elementi within a predetermined narrow range approximating the pressure of the vapor produced in said elements so that stresses on the heated elements of said generator are limited and only the cool casing is required to withstand high pressure.

2. In a vapor generator, a pressure resistant casing enclosing a combustion chamber wherein high pressures approximating the vapor pres- 2S sures generated in said generator may be maintained, means for supplying fuel to said chamber, means for delivering a combustion supporting gas into said chamber for combustion of the fuel supplied thereto, a vapor generating element within said chamber, and means responsive to decrease and increase of the pressure of the vapor generated in said vapor generating element relative to the pressure of the combustion gases within said chamber and operatively connected to said means for supplying fuel and to said means for delivering said combustion supporting gas to said chamber for increasing and decreasing the supply of the fuel to said chamber to increase and decrease the pressure of the generated vapor and concomitantly to control the delivery of said combustion supporting gas to said chamber to maintainl the pressure of the combustion gases within said chamber in a predetermined relation to the pressure of said vapor.

3. In a vapor generator, a pressure resistant casing enclosing a combustion chamberk wherein high pressures approximating the vapor pressures generated in said generator may be maintained, means for supplying fuel to said chamber, means for delivering a coinbustionsupporting gas into said chamber for combustion of the uel supplied thereto, a vapor generating element within said chamber, and means responsive to decrease and increase of the pressure of the vapor generated in said vapor generating element relative to the pressure of the combustion gases within said chamber and operatively connected to said means for supplying fuel and to said means for delivering said combustion supporting gas to said chamber for increasing and decreasing the suppiy of the fuel to said chamber to increase and decrease the pressure of the generated vapor and concomitantly to control the delivery of said combustion supporting gas to said chamber to decrease and increase the pressure of the combustion gases within said chamber to maintain the pressure of the combustion gases within a predetermined narrow range with respect to the pressure of the generated vapor.

4. In a vapor generator, a pressure resistant casing enclosing a combustion chamber wherein high pressures approximating the vapor pressures generated in said generator may be maintained, means for supplying fuel to said chamber, means for delivering a combustion supporting gas into said chamber for combustion of the fuel supplied thereto, a vapor generating element within said chamber, means responsive to variations from a predetermined difference between the vapor preseure generated in said Vapor generating element and the pressure of the combustion gases within said chamber and operatively connected to said means for supplying said fuel for controlling the supply of said fuel to control the pressure of the generated vapor, and means responsive to variations in the pressure of the gases in said combustion chamber and operatively connected to said means for delivering said combustion supporting gas into said chamber for controlling the delivery of said combustion supportingr gas concomitantly with the control of the fuel supplied to said combustion chamber so as to maintain said predetermined difference between the vapor pressure and the pressure of the combustion gases within said chamber substantially constant. l

5. In a vapor generator, a pressure resistant casing enclosing a combustion chamber wherein high pressures approximating the vapor pressures generated in said generator may be maintained,

, pressure of the combustion gases within said chamber and operatively connected to said means for supplying fuel to said chamber for increasing and decreasing the supply of fuel to said chamber to increase and decrease the pressure of" said generated vapor relative to the pressure of the combustion gaseswithin said chamber, and means responsive to variations in the pressure of said combustion gases within said chamber and operatively connected to said means for delivering said combustion supporting gas thereto for operating said delivery means to maintain said pressure of said combustion gases within said chamber substantially constant. 6. in a vapor generator, a pressure resistant casing Aenclosing ay combustion chamber wherein' high pressures approximating the` vapor pressures generated in said generator may be maintained, means for supplying fuel to said chamber, means for delivering a combustion supporting gas into said chamber for combustion of the fuel supplied thereto, a Vapor generating element within said chamber, means responsive to cle--` crease and increase of the pressure of the Vvapor generatediri said vapor generating element relative to the pressure of the combustion gases within said chamber and operatively connected tov said means for supplying fuel and to said meansA for delivering said combustion supporting gas to said chamber for increasing and decreasing the supply of the fuel and the delivery of said combustion supporting gas to said chamber to increase and decrease the heat of'said comvbustion gases Within said chamber to effect increase and decrease of the pressure of the generated vapor relativeto said pressure of the combustion gases, and means responsive to variations in the pressure of the combustion'gases Within said chamber and operatively connected to means for delivering said combustion supporting gasto said chamber for effecting delivery of combustion supporting gas to said chamber so as to maintain said pressure within said combustion chamber substantially constant.

7. Ina boiler for working with a combustion air pressure of 5 to 120 lig/cm.2 and for generating a steam" pressure, a regulatory apparatus comprising a spring piston connected at one end to said air. pressure and on the other end to said steam pressure, control means for feeding fuel and combustion supporting air to the boiler, ccnnecting means between said piston and said control means to regulate the supply of fuel and combustion supporting air in response to displacement of the piston resulting from deviations from a substantially equal air pressure and steam pressure.

8. The improved method of operating a vapor generating system wherein a combustion cham-Y cer and vapor generating elements are enclosed within a Ypressure resisting casing, which comprises delivering fuel and a combustion supper*- ing gas to and effecting combustion of fuel said'chamber to produce high temperature combustion gases of high pressure therein, and controlling the feeding of fuel and combustion porting gas to saidcombustion chamber while withdrawing the combustion gases therefrom in generating elements.

such manner as to maintain the pressure of the combustion gases in said chamberwithin a predetermined narrow range with respect to the pressure of the vapor generated in said vapor 9. The method of operating a vapor generating system wherein a combustion chamber and a Vapor generating element are enclosed Within a pressure resisting casing, which comprises supplying fuel to said chamber for 'combustion therein to generate the vapor by the heat of said fuel at a pressure elevated substantially above atmospheric pressure, delivering a combustion supporting gas into said chamber for supp-ort of the combustion of the fuel supplied thereto to produce high temperature combustion gases at a pressure of the degree of the pressure of the generated vapor, increasing and decreasing the supply of the fuel to said combustion chamber in rc sponse to decrease and increase in the pressure ofv saidy vapor relative to the pressure of said combustion gases in said chamber to increase and decrease the pressure of the generated vapor, and concomitantly decreasing and increasing the delivery of the combustion supporting gas to said chamber to decrease and increase the pressure of the combustion gas in said'chamber, thereby to Vmaintain a substantially constant diiferencebetween said vapor pressureand the pressure of the` combustion gases within said chamber.

1G. The method of operating a 'vapor generatingssystem wherein a combustion chamber and a vapor generating element therein are enclosed within a pressure resisting casing which comprises supplying fuel to said chamber for combustion therein to generate the vapor by the heat of said fuel at a pressure elevated substantially above atmosphere pressure, deliver-inge combustion supporting gas into said chamber for support of the combustion of the fuel supplied. thereto to produce high temperature combustion gases ata pressure of the degree of the pressure of the generated vapor, increasing and decreasing the supply of fuel and the delivery of said combustion supporting gas to said chamber in response to decrease'and increase in the pressure of said vapor relative to the pressure of lsaid combustion gases in said chamber to increase and decrease the pressure of the generated vapor, and controlling the deliveryof combustion supporting gas to said chamber s0 as to maintain the pressure of the combustion gases therein substantially constant.

l1, The method of operating a steam generatingrsystem wherein a combustion chamber is yenclosed within pressure confining wi s 21.11.,., steam generating tubes are positioned withinsaid chamber in heat insulating'rel'a'tion/ to sait-- walls which comprises delivering a combustion supporting gas and a fuel to said chamber, ef-v ated steam so as to maintain said pressures in a predetermined relation to each other.

l2. in a vapor generator, a casing encio ing a combustion chamber, a vapor generating eicment within said cha Jer generating vapor at a pressure substa tially above atmospheric pres-` sure, said casing being constructed to conine the combustion gases within said chamber at a pressure substantially the same as the pressure of said vapor, means for suppiying fuei to said chamber ior combustion therein, means for deiivering a combustion supporting gas into said chamber against the pressure therein for support of the combustion the fuel supplied thereto, means for withdrawing the generated vapor oni said 'vapor generating element, i ieans ici wishirawing said combustion gases from said com ion chamber, means responsive to vari: 'tions oi the pressure of said vapor relative to the pressure of the combustion gases and operatively connected to said means for withdrawing said vapor and to said means for withdrawing said combustion gases for controlling the withdrawal of said vapor and of said combustion gases so as to maintain the pressure of said vapor sub-stan tiaily in a predetermined relation to the pressure said combustion gases.

13. In a vapor generator, a casing enclosing a combustion chamber, a vapor generating element within said chamber for generating vapor at a pressure substantially above atmospheric pressure, said casing being constructed to confine the combustion gases within said chamber at a pressure substantially the same as the pressure of the vapor generated in said vapor generating element, means for supplying fuel to said chamber for combustion therein, means for delivering a combustion supporting gas into said chamber against the pressure therein support of the combustion of the fuel supplied thereto, means responsive to variations in the pressure or" the generated vapor and operatively connected to said means for supplying fuel to said chamber and to said means for delivering said combustion supporting gas into said chamber for controlling the supply of fuel and the delivery of said gas to control the pressure of the generated vapor, means for withdrawing from said vapor generating element the generated vapor substantially at the pressure at which it is generated, means for withdrawing from said combustion chamber the combustion gases substantially at the pressure within said chamber, means responsive to variations of the pressure of said vapor relative to the pressure of the combustion gases and operatively connected to said means for withdrawing said vapor and to said means for withdrawing said combustion gases for controlling the withdrawal of said vapor and of said combustion gases so as to maintain said pressure of said generated vapor substantially in a predetermined relation to the pressure of said combustion gases.

1li. In a vapor generator, a casing enclosing a combustion chamber, a vapor generating element within said chamber for generating vapor at a pressure substantially above atmospheric pressure, said casing being constructed to conne the combustion gases within said chamber at a pressure of the degree of the pressure of the vapor to be generated in said generating element, means for supplying fuel to said chamber for combustion therein, means for delivering a combustion supporting gas into said chamber against the pressure therein for support of the combustion of the fuel supplied thereto, means responsive to increases and decreases in the pressure of the generated vapor and operatively connected to said means for supplying fuel to said chamber and to said means for delivery of said combustion supporting gas into said chamber for decreasing and increasing the supply of fuel and the delivery of said combustion supporting gas to said chamber to decrease and increase the heat of said combustion gases to decrease and increase the pressure of said generated vapor, thereby substantially to maintain a predetermined vapor pressure, means for withdrawing from said vapor generating element the generated vapor substantially at the pressure at which it is generated, means for withdrawing from said combustion chamber the combustion gases substantially at the pressure within said chamber, means responsive to variations of said vapor pressure relative to said pressure of the combustion gases and operatively connected to said means for withdrawing said vapor and to said means for withdrawing said combustion gases for controlling the withdrawal of said vapor and of said combustion gases so as to maintain the pressure of said generated vapor substantially in a predetermined relation to the pressure of said combustion gases.

l5. In a water tube boiler, a pressure resistant casing enclosing a combustion chamber wherein superatmospheric pressures approximating the steam pressures generated in said boiler may be maintained, means for supplying fuel to said chamber, means for delivering air under pressure into said chamber for combustion of the fuel supplied thereto, steam generating tubes within said chamber, and means responsive to deviations from a predetermined difference in the steam pressure with respect to the pressure of said combustion gases within said chamber for controlling the supp-ly of the fuel and of the air in such a manner as to control the pressure of the steam and the pressure of the combustion gases vithin the chamber so as to maintain the difference between said steam pressure and the pressure of said combustion gases within said chamber substantially constant.

16. ln a vapor generator, a casing enclosing a combustion chamber capable of confining gases therein at a pressure approximating the pressure of the vapor to be generated said generator, a vapor generating element within said chamber, means for supplying fuel to said chambermeans for delivering a combustion supporting gas under pressure into said chamber for combustion of the fuel therein to produce combustion gases in heat exchanging reiation to vapor generating element at a temperature to generate vapor in said element at a selected pressure and to develop pressure of said combustion gases in said combustion chamber approximating said vapor pressure, means for withdrawing combustion gases from said combustion chamber cooperating with said means for delivering combustion supporting gas thereto so as to produce iiow of gases through said chamber, means operabie to control said flow of said gases so as to control the pressure thereof within said combustion chamber, and means responsive to the pressure of the vapor generated in said vapor generator reiative to the pressure of the gases within said combustion chamber and cooperating with said means for supplying fuel to said chamber and with said gas flow controlling means for controliing the flow of said gases through and the pressure thereof in said chamber in relation to the generation of vapor in said vaporgenerating element so as to 

